Lieutenant Natasha "Tasha" Yar is a fictional character who mainly appeared in the first season of the American science fiction television series Star Trek: The Next Generation. Portrayed by Denise Crosby, she is chief of security aboard the Starfleet starship USS Enterprise-D. The character's concept was originally based upon the character of Vasquez from the 1986 film Aliens. Following further development she became known first as Tanya, and then Tasha. Crosby had originally auditioned for the role of Deanna Troi, while Rosalind Chao became a favorite for Tasha. After Marina Sirtis auditioned for the role, the show's creator Gene Roddenberry decided to switch the roles for the actresses, with Sirtis becoming Troi and Crosby becoming Yar (Chao would later appear on the series in a recurring role as Keiko O'Brien).The character first appeared in the series' pilot episode, "Encounter at Farpoint". After Crosby decided to leave the show, Yar was killed by the creature Armus in "Skin of Evil", the 23rd episode of the season. She was written back into the show for a guest appearance in the third season episode "Yesterday's Enterprise", in which the timeline was altered so that she did not die, and again in the final episode of the series "All Good Things...", in events set prior to the pilot.She was described as a forerunner to other strong women in science fiction, such as Kara Thrace from the 2004 version of Battlestar Galactica, while providing a step between the appearances of female characters in The Original Series to the command positions they have in Star Trek: Deep Space Nine and Voyager. Questions were raised over the sexuality of the character, and it was thought that the events in the episode "The Naked Now" were designed to establish her heterosexuality. The manner of her first death was received with mostly negative reviews. One critic called it typical of the death of a Star Trek security officer, and the scene was also included in a list of tasteless sci-fi deaths.